Ascorbate−glutathione cycle involving in response of Bangia fuscopurpurea (Bangiales, Rhodophyta) to hyposalinity

Bangia fuscopurpurea is a widespread intertidal seaweed that is commercially cultured in China. This seaweed is frequently exposed to hyposalinity stress, but little is known about the adaptation mechanisms. Ascorbate−glutathione (AsA−GSH) cycle plays important roles in many organisms under a variety of abiotic stress, including hyposaline stress. In this study, we investigated the response of key metabolites and enzymes involved in the AsA−GSH cycle of B. fuscopurpurea under hyposalinity, with the addition of exogenous GSH and Lbuthionine-sulfoximine (BSO). The quantification of BfAPX gene expression was assessed across varied treatment regimens. And the putative interaction proteins of BfAPX were screened by yeast two hybrid system. It was found that under hyposalinity (15 and/or 0 psu), the content of reduced glutathione (GSH), total glutathione (GSH+ oxidized glutathione, GSSG) and cysteine, the ratio of GSH/GSSG and ascorbic acid (AsA)/ dehydroascorbic acid (DHA), and the activity of ascorbic acid peroxidase (APX) and monodehydroascorbate reductase (MDHAR) was significantly up-regulated. The hyposality-promoted GSH/GSSG was weakened while the glutathione reductase (GR) activity was promoted by adding exogenous GSH and BSO. The hyposality-promoted AsA/DHA ratio was strengthened by exogenous GSH but weakened by BSO. The dehydroascorbate reductase (DHAR) activity had no significant changes either with or without exogenous GSH under all salinities, while DHAR activity together with DHA content was enhanced by BSO. The expression of APX gene markedly increased under hyposalinity+BSO treatment. Putative interacting proteins of APX, including glutamate dehydrogenase 1a and fructose diphosphate aldolase, were identified through screening. The results indicated that the AsA−GSH cycle was involved in response of B. fuscopurpurea to hyposalinity by means of increasing GSH/GSSG ratio (through promoting GSH biosynthesis pathway and GSH regeneration from GSSG by GR catalyzation) and AsA/DHA ratio (promoting AsA regeneration through MDHAR). These findings would contribute to improve the aquaculture of this promising economic species and unveil how intertidal seaweeds address the global climate challenges

TNFα Contributes to Diabetes Impaired Angiogenesis in Fracture Healing

Diabetes increases the likelihood of fracture, interferes with fracture healing and impairs angiogenesis. The latter may be significant due to the critical nature of angiogenesis in fracture healing. Although it is known that diabetes interferes with angiogenesis the mechanisms remain poorly defined. We examined fracture healing in normoglycemic and streptozotocin-induced diabetic mice and quantified the degree of angiogenesis with antibodies to three different vascular markers, CD34, CD31 and Factor VIII. The role of diabetes-enhanced inflammation was investigated by treatment of the TNFα-specific inhibitor, pegsunercept starting 10 days after induction of fractures. Diabetes decreased both angiogenesis and VEGFA expression by chondrocytes. The reduced angiogenesis and VEGFA expression in diabetic fractures was rescued by specific inhibition of TNF in vivo. In addition, the TNF inhibitor rescued the negative effect of diabetes on endothelial cell proliferation and endothelial cell apoptosis. The effect of TNFα in vitro was enhanced by high glucose and an advanced glycation endproduct to impair microvascular endothelial cell proliferation and tube formation and to stimulate apoptosis. The effect of TNF, high glucose and an AGE was mediated by the transcription factor FOXO1, which increased expression of p21 and caspase-3. These studies indicate that inflammation plays a major role in diabetes-impaired angiogenesis in endochondral bone formation through its effect on microvascular endothelial cells and FOXO1

Enhancement of the Tumor Suppression Effect of High-dose Radiation by Low-dose Pre-radiation Through Inhibition of DNA Damage Repair and Increased Pyroptosis

Radiation therapy has been a critical and effective treatment for cancer. However, not all cells are destroyed by radiation due to the presence of tumor cell radioresistance. In the current study, we investigated the effect of low-dose radiation (LDR) on the tumor suppressive effect of high-dose radiation (HDR) and its mechanism from the perspective of tumor cell death mode and DNA damage repair, aiming to provide a foundation for improving the efficacy of clinical tumor radiotherapy. We found that LDR pre-irradiation strengthened the HDR-inhibited A549 cell proliferation, HDR-induced apoptosis, and G2 phase cell cycle arrest under co-culture conditions. RNA-sequencing showed that differentially expressed genes after irradiation contained pyroptosis-related genes and DNA damage repair related genes. By detecting pyroptosis-related proteins, we found that LDR could enhance HDR-induced pyroptosis. Furthermore, under co-culture conditions, LDR pre-irradiation enhances the HDR-induced DNA damage and further suppresses the DNA damage-repairing process, which eventually leads to cell death. Lastly, we established a tumor-bearing mouse model and further demonstrated that LDR local pre-irradiation could enhance the cancer suppressive effect of HDR. To summarize, our study proved that LDR pre-irradiation enhances the tumor-killing function of HDR when cancer cells and immune cells were coexisting